Isolation and Characterization of the First Temperate Virus Infecting Psychrobacillus from Marine Sediments

Viruses are far more abundant than cellular microorganisms in the marine ecosystem. However, very few viruses have so far been isolated from marine sediments, especially hydrothermal vent sediments, hindering the understanding of the biology and ecological functions of these tiny organisms. Here, we report the isolation and characterization of a temperate bacteriophage, named PVJ1, which infects Psychrobacillus from a hydrothermal vent field in Okinawa Trough. PVJ1 belongs to the Myoviridae family of the order Caudovirales. The tailed phage possesses a 53,187 bp linear dsDNA genome, with 84 ORFs encoding structural proteins, genome replication, host lysis, etc. in a modular pattern. The phage genome is integrated into the host chromosome near the 3 '-end of deoD, a gene encoding purine nucleoside phosphorylase (PNP). The phage integration does not appear to disrupt the function of PNP. The phage DNA is packaged by the headful mechanism. Release of PVJ1 from the host cell was drastically enhanced by treatment with mitomycin C. Phages encoding an MCP sharing significant similarity (>= 70% identical amino acids) with that of PVJ1 are widespread in diverse environments, including marine and freshwater sediments, soils, artificial ecosystems, and animal intestines, and primarily infect Firmicutes. These results are valuable to the understanding of the lifestyle and host interactions of bacterial viruses at the bottom of the ocean.

Automated summary

Viruses are more abundant in the marine ecosystem than cellular microorganisms, and yet there is a lack of knowledge about viruses isolated from marine sediments, particularly hydrothermal vent sediments. This study reports the isolation and characterization of a temperate bacteriophage called PVJ1, which infects Psychrobacillus from a hydrothermal vent field. The phage possesses a linear dsDNA genome with multiple encoding regions for various functions. The integration of the phage genome into the host chromosome does not disrupt the host gene function. Additionally, similar phages to PVJ1 are found in diverse environments and primarily infect Firmicutes. This research contributes valuable insights into the biology and interactions of bacterial viruses in the ocean bottom.